Bobbin chuck for the shaftless retention of cylindrical bodies of rotation

ABSTRACT

A chuck for engaging a rotatable body includes an elongated inner core formed with a plurality of recesses in which thrust members are mounted for pivoting movement about pivotal axes spaced a small distance from the longitudinal axis of the inner core. Jaws are provided, each supported on two of the thrust members and juxtaposed with an inner circumferential surface of a hole in the rotatable body, and an annular cage interconnects the thrust members and synchronizes their pivoting movements about their pivotal axes. Springs urge the jaws toward the inner core, and movement of the thrust members toward their erected positions results in engagement of the jaws with the internal surface and in centering of the hole with respect to the chuck. The extent of radially outward movement of the jaws is limited by projections on the chuck which bound a clearance in which the jaws are free to move.

United States Patent Mosser Oct. 7, 1975 [75] Inventor: Wilhelm Mosser, Darmstadt,

Germany [73] Assignee: Dr. Otto C. Strecker KG, Hesse,

Germany [22] Filed: Feb. 14, 1974 [21] App]. No: 442,593

[30] Foreign Application Priority Data Feb. 22, 1973 Germany 2308755 [52] U.S. Cl. 242/68.4; 242/72; 279/2 [51] Int. Cl B65h 75/24 [58] Field of Search 242/68.4, 68.2, 72, 46.5.,

[56] References Cited UNITED STATES PATENTS 2,468,867 5/1949 Collins 242/72 UX 3,018,977 1/1962 Skallquist 242/72 3281092 10/1966 Schultz et al.. .1 242/72 3,387,799 6/1968 Wilson 242/72 3.695.539 10/1972 Lindstaedt .1 242/72 Primary Examiner-John W. Huckert Assistant Examiner-John M. Jillions Attorney, Agent, or FirmMichael S. Striker [57] ABSTRACT A chuck for engaging a rotatable body includes an elongated inner core formed with a plurality of recesses in which thrust members are mounted for pivoting movement about pivotal axes spaced a small distance from the longitudinal axis of the inner core. Jaws are provided, each supported on two of the thrust members and juxtaposed with an inner circumferential surface of a hole in the rotatable body, and an annular cage interconnects the thrust members and synchronizes their pivoting movements about their pivotal axes. Springs urge the jaws toward the inner core, and movement of the thrust members toward their erected positions results in engagement of the jaws with the internal surface and in centering of the hole with respect to the chuck. The extent of radially outward movement of the jaws is limited by projections on the chuck which bound a clearance in which the jaws are free to move.

13 Claims, 3 Drawing Figures US. Patent Oct. 7,1975 Sheet 1 of2 3,910,520

Fig. I

US. Patent Oct. 7,1975 Sheet2 of2 3,910,520

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i Fig. 3

BOBBIN CHUCK FOR THE SHAFILESS RETENTION OF CYLINDRICAL BODIES OF ROTATION Bobbin chucks are used for the supporting rotatable cylindrical bodies, for example coiling bobbins used in a winding machine for paper, film, fabric and like coils. The bobbins, which are usually made of cardboard, and are provided with the coils or webs, are inserted into pay-out racks for further processing of the coiled webs, two coaligned axially slidable bobbin chucks being rotatably journalled in the racks and being inserted from both ends into the open bobbins to a depth of 110 to 160 mm, depending on the internal bobbin diameter, thus retaining the respective bobbin between them and being automatically tensioned by engagement'with the internal wall of the bobbin. The shafts which support the bobbin chucks are coupled outside the bearings with braking devices which apply a braking torque to the bobbin and the coil thereon in order to produce the web tension required for paying out and in order to apply an even greater braking torque during rapid deceleration of the inertial mass of the coil when the machine is stopped.

It is the object of the invention to construct a bobbin chuck so that it is able to satisfy the following requirements which cannot be readily combined with each other:

It must be able to hold the bobbin with the heavy coil with minimum torque and must be able to apply centered gripping action; the engaged force should be proportional to the torque; the engagement range should be as large as possible, and should cover at least mm difference of diameter to enable bobbins with different internal diameters, for example those with an internal diameter of 70 mm or 76 mm to be mounted on the same bobbin chuck and without the need for changing the latter;

It must nevertheless be able to reliably transmit the braking torques which are required to apply a steady web pull on to the coil, and must not destroy the cardboard bobbins.

The invention solves the problem by providing a bobbin chuck with an inner central chucking member having a plurality of thrust members which are supported in recesses of the said chucking member, are circumferentially pivotable and are coupled to each other through an annular cage, and by the provision around the annular cage of a plurality of jaws each of which is mounted on two thrust members which are pivotably supported proximate to the axis of the chucking member in recesses thereof that are axially offset in pairs for the thrust members of a first jaw relative to the thrust members of a second jaw. The fact that the thrust members which support the jaws are journalled near the axis of the member results in a flat rise of the thrust characteristic so that a relatively small braking torque in con-. junction with the intercoupling of all thrust members via the annular cage already achieves perfect centring of the bobbin. The use of jaws with a large surface area and substantially adapted to cover the entire circumference of the chuck results in lower specific surface pressure on the internal wall of the bobbin and thus extends the working life thereof.

The advantageous arrangement for supporting the thrust members near the axis of the chucking member is possible only as a result of the inventive distribution of the recesses in which they are accommodated and which are disposed in pairs and in an axially offset relation in adjacentlysituated cross-sections of the chucking member. A substantial number of recesses is required in the chucking member if this is provided with a plurality, more particularly three or four, jaws because each of these is supported by two thrust members and it is only this distribution which allows a sufficient load-bearing cross-section to be retained over the entire length of the chucking member.

According to the invention it is possible for the supporting positions to be situated so close to the axis of the chucking member that the pivoting centers of the thrust members are disposed in the recesses of the chucking member on the surface of an imaginary cylinder which is concentric with the axis of the chucking member, the diameter of the cylinder being approximately equal to the thickness of the thrust members. If a narrow partition is to remain between the two recesses that are disposed in one cross-sectional plane, the diameter of the imaginary cylinder must be made larger than the thickness of the thrust members by the wall thickness of the said partition.

In a preferred embodiment the thrust members are constructed as tappets with rounded end faces and are loosely inserted in segmental pockets which merge into spherical seats in the chucking member. Sliding friction occurs substantially only in the aforementioned spherical cups when the chuck is stressed thus achieving a high efficiency for the bobbin chuck according to the invention: approximately of the torque applied by the bobbin is added to the radial stressing force.

The segmental angle of the pockets advantageously amounts to between 30 and 45, preferably 40; these values, which define the pivoting angle of the thrust members, achieve a maximum clamping range while maintaining the flat thrust characteristic.

ln an embodiment which is particularly simple in terms of manufacturing technology, the inner rounded end face of the tappet is formed on an inserted, hardened steel ball. The shape of this precisely round ball is automatically assumed by the less precisely round spherical seat at the base of the pocket which acoommodates the tappet namely by virtue of the large clamping thrust which results in consolidation of the surface.

One embodiment of the invention is described hereinbelow by reference to the accompanying drawing in which:

FIG. 1 is a cross-section through a bobbin with four chuck jaws;

FIG. 2 is a longitudinal section through the chuck along the line IllI of FIG. 1, and

FIG. 3 is a cross-section similar to FIG. 1 through a bobbin chuck which is elTective in both directions of rotation.

A bronze annular cage 3 is rotatably supported on a chuck member or core 1 of the bobbin chuck one end face of which has an annular flange 2 welded upon it. Tappets 4 which are configurated as rod shaped thrust members for pads for the chuck jaws 5 are situated in bores which are axially and longitudinally offset around the circumference of the aforementioned annular cage 3. Each jaw 5 is supported by two tappets 4 which are inserted into blind holes 5.1 of the respective jaw 5.

Segmental pockets or recesses 6 are milled into the core 1 to accommodate the tappets 4. As may be seen by reference to FIG. 1 the lateral offset configuration enables two pockets 6 to be accommodated in one cross-section; the pockets 6 are also axially offset in pairs as may be seen by reference to FIG. 2. The depth of the pockets 6 is such that the pivoting point S of the respective [tappet 4 inserted therein, as seen from the associated jaw 5, is laterally offset by an amount e with respect to the center axis of the cylindrical core 1 (FIG. 1). This eccentricity e of the pivoting point S with respect to the axis of the chuck determines the excursion of the jaw 5 (FIG. 1 left top) within the pivoting angle ,8 and thus results in the flat rise of the thrust characteristic.

Each tappet 4 comprises a stem 4.1 the end'face of which that is inserted into the blind hole 5.1 has a rounded surface 4.2 ground upon it, while the end face that is inserted in the pocket 6 has a steel ball 4.3 inserted in it by means of a spigot 4.4. A spherical cup or seat 6.1 is milled into the pocket base to matchthe aforementioned hall 4.3. As already mentioned, the ball 4.3 shapes the seat 6.1 underthe effect of the large chucking pressure. A lead containing lubricant prevents frictional corrosion.

The jaws 5 are loosely supported on the tappets 4 and are retained by means of tension springs. Annular springs 7, for example in the form of helical springs, are inserted into annular grooves 5.2 of the jaws 5.:toexpand when the chuck is stressed and to return the jaws V 5 when the chuck is released.

The free end face of. the core 1 is provided with a cover 8 that extends at the end over the annular cage 3 and the jaws 5 (FIG. 2):. Annular projections 5.3 are machined on the end faces of the jaws 5 and are positioned'opposite to and at aradial distance from corresponding projections 8.1 on the cover 8 and projections 2.1 on the flange ring 2. The radial distance determines the maximum excursion of the jaws 5 to that within the.

pivoting angle B so that the jaws 5 cannot be removed.

ratchet pawl 9 can be manually disengaged from teeth 31 by depressing a pin 10. The annular springs 7 can be replaced by individual tensionsprings suspended betweenevery two adjacent jaws 5..

While the embodiment described hereinabove is active in only one direction of rotation, it is possible for the idea of the invention to beextended to bobbin chucks active in both directions of rotation. FIG. 3 shows a cross-section similar to FIG. 1 with only one thrust member 14 in only onepocket 16; the annular cage 3 and the jaws 5 have been omitted. For each direction of rotation the pocket 16 must be provided with a separate bearing (spherical seat 16.1) that has the eccentricity e and the thrust member 14 must be provided with two bearing balls 14.3 which are symmetrically disposed on both sides of a stem 14.1. The circular broken lines indicatethat the radialdistance of the apex of a rounded end face 14.2 of the thrust member 14 from the centralaxis of the core 11 increaseswhen the tion aboutone of the pivoting points'F F 1; A chuck for engaging a rotatable body having a hole bounded by an inner. circumferential surface, comprising an elongatedinner core provided with :a plurality of recesses extending from the proximity of the longitudinal axis of said inner core to the outer circumference of the latter; a plurality of thrust members each having one end portion accommodated in one of said recesses, and a free end portion located radially outwardly of said outer circumference of said inner core;.means for'mounting the respective thrust members in the respective recesses for pivoting movements about pivoting axes which are proximate, parallel to and radially offset from said longitudinal axis, between respective retracted positions and erected positions; a plurality of jaws, each supported on said free end por-. tions of two of said thrust members and having an outer engaging surface juxtaposable with said inner surface; and means circumferentially interconnecting said thrust members so as to synchronize said pivoting movements thereof about their respective axes at least when a force is applied to at least one of said thrust members tending to move the same toward said erected position thereof, whereby said outer engaging surfaces of said jaws engage said innersurface and center the.

same with respect to said longitudinal axis of said inner core.

2. A chuck as defined in claim 1, wherein said two thrust members on which a respective jaw is supported I are spaced fromfone another longitudinally of said said longitudinal axis of said inner core; and wherein the respective pivoting axis is offset from said longitudinal .axis by a distance which substantially corresponds to said dimension.

5. A chuck as defined in claim 1, wherein said mounting means includes a spherical seat in each of said recesses, and a spherical surface at the one end portion of the respective thrust member and engaging said seat.

6. A chuck as defined in claim 1; and further comprising a hardened steel ball connected to said one end portion; and wherein said mounting means includes a spherical seat in each of said recesses and the spherical surface of said hardened" steel ball which engages said spherical seat. I

' 7. A chuck as defined in claim 1, wherein each of said recesses extends parallel to a plane normal to said longitudinal axis and diverges in the radially outward di+ rection of said inner core.

8. A chuck as defined inclaim 7, wherein the angle of divergence of, saidrecess amounts to between 30 and 45. 1

9. A chuck asdefined in; claim 1, wherein. said interconnecting means includes an annular cage mounted on said inner core for angular displacement withirespect thereto and having a plurality of apertures for partly receiving said free end portions of said thrust members.

the same radially inwardly toward said inner core.

12. A chuck as defined in claim 11, wherein said jaws are formed with annular grooves in the regions of their engaging surfaces; and wherein said tension springs are lodged in said annular grooves.

13. A chuck as defined in claim 1, wherein said jaws are formed with blind holes for receiving said free end portions of said thrust members; and wherein said free end portions are formed with additional spherical surfaces engaging said jaws in said blind holes.

UNITED STATES PATENT AND TRADEMARK OFFICE QTTFTCATE OF PATENT NO. I 3,910,520

DATED I October 7, 1975 INVENTOR(S) Wilhelm MESsser It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading [75] the name of the inventor should read Wilhelm Mr'isser In the heading [73] the narnes and addresses of the assignees should read Dr. Otto C. Strecker KG, Pfungstadt/ Hessen, Federal Republic of Germany Germany Signed and Sealed this i th'rte th [SEAL] l D y of Aprtl1976 A lies I:

RUTH C. MASON ummissiumr 01' Parents and Trademarks 

1. A chuck for engaging a rotatable body having a hole bounded by an inner circumferential surface, comprising an elongated inner core provided with a plurality of recesses extending from the proximity of the lonGitudinal axis of said inner core to the outer circumference of the latter; a plurality of thrust members each having one end portion accommodated in one of said recesses, and a free end portion located radially outwardly of said outer circumference of said inner core; means for mounting the respective thrust members in the respective recesses for pivoting movements about pivoting axes which are proximate, parallel to and radially offset from said longitudinal axis, between respective retracted positions and erected positions; a plurality of jaws, each supported on said free end portions of two of said thrust members and having an outer engaging surface juxtaposable with said inner surface; and means circumferentially interconnecting said thrust members so as to synchronize said pivoting movements thereof about their respective axes at least when a force is applied to at least one of said thrust members tending to move the same toward said erected position thereof, whereby said outer engaging surfaces of said jaws engage said inner surface and center the same with respect to said longitudinal axis of said inner core.
 2. A chuck as defined in claim 1, wherein said two thrust members on which a respective jaw is supported are spaced from one another longitudinally of said inner core, and parallel one another.
 3. A chuck as defined in claim 2, wherein two additional thrust members on which another jaw is supported are accommodated in recesses which are spaced from the respective recesses accommodating the firstmentioned two thrust members longitudinally of said inner core.
 4. A chuck as defined in claim 1, wherein each of said thrust members has a dimension in a plane normal to said longitudinal axis of said inner core; and wherein the respective pivoting axis is offset from said longitudinal axis by a distance which substantially corresponds to said dimension.
 5. A chuck as defined in claim 1, wherein said mounting means includes a spherical seat in each of said recesses, and a spherical surface at the one end portion of the respective thrust member and engaging said seat.
 6. A chuck as defined in claim 1; and further comprising a hardened steel ball connected to said one end portion; and wherein said mounting means includes a spherical seat in each of said recesses and the spherical surface of said hardened steel ball which engages said spherical seat.
 7. A chuck as defined in claim 1, wherein each of said recesses extends parallel to a plane normal to said longitudinal axis and diverges in the radially outward direction of said inner core.
 8. A chuck as defined in claim 7, wherein the angle of divergence of said recess amounts to between 30* and 45*.
 9. A chuck as defined in claim 1, wherein said interconnecting means includes an annular cage mounted on said inner core for angular displacement with respect thereto and having a plurality of apertures for partly receiving said free end portions of said thrust members.
 10. A chuck as defined in claim 1; and further comprising means for limiting the extent of radial movement of said jaws with respect to said inner core, said limiting means including abutments connected with said inner core, radially spaced therefrom and defining therewith clearances for partially receiving said jaws with freedom of movement radially and circumferentially of said inner core.
 11. A chuck as defined in claim 1; and further comprising means for urging said thrust members toward their retracted positions, said urging means including tension springs interconnecting said jaws and urging the same radially inwardly toward said inner core.
 12. A chuck as defined in claim 11, wherein said jaws are formed with annular grooves in the regions of their engaging surfaces; and wherein said tension springs are lodged in said annular grooves.
 13. A chuck as defined in claim 1, wherein said jaws are formed with blind holes for receiving said free end portions of said thrust members; and wherein said free end portionS are formed with additional spherical surfaces engaging said jaws in said blind holes. 